Sensor unit

ABSTRACT

This sensor unit includes a base having a substantially-rectangular planar shape including a first side and a second side that are substantially orthogonal to each other, and a plurality of first sensors provided on the base and arranged on a first axis. The first axis is substantially parallel to the first side and passes through a center position of the base.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.15/641,529 filed Jul. 5, 2017, which is based on and claims priorityunder 35 U.S.C. 119 from Japanese Patent Application No. 2016-140085filed on Jul. 15, 2016, Japanese Patent Application No. 2016-241461filed on Dec. 13, 2016 and Japanese Patent Application No. 2017-000854filed on Jan. 6, 2017. The contents of the above applications areincorporated herein by reference.

BACKGROUND

The invention relates to a sensor unit in which a plurality of sensorsare disposed on a base.

In general, a sensor unit (a sensor package) has been known in which aplurality of sensors, an integrated circuit, and so forth are providedon a base (for example, see Japanese Unexamined Patent ApplicationPublication No. 2009-63385). As such a sensor package, an angledetection sensor has been proposed that detects a rotary operation of arotating body such as an axle (for example, see Japanese UnexaminedPatent Application Publication No. 2006-208255).

SUMMARY

Incidentally, miniaturization and an improvement in detection accuracyof such a sensor unit have been strongly desired in recent years.

However, with a progress in size reduction, stress due to a distortionof a base resulting from a change in environmental temperature, heatgeneration of an integrated circuit, and so forth is applied to eachsensor, which in turn may possibly cause an adverse effect on an outputof each of the sensors.

It is therefore desirable to provide a sensor unit in which a decreasein detection accuracy due to a factor such as thermal stress is smalland thus having superior reliability.

A first sensor unit according to one embodiment of the inventionincludes: a base having a substantially-rectangular planar shapeincluding a first side and a second side that are substantiallyorthogonal to each other; and a plurality of first sensors provided onthe base and arranged on a first axis. The first axis is substantiallyparallel to the first side and passes through a center position of thebase.

In the first sensor unit according to one embodiment of the invention,the plurality of first sensors are arranged on the first axis. The firstaxis on the base is substantially parallel to the first side and passesthrough the center position of the base. Thus, the plurality of firstsensors are placed at respective positions in which a distortion of thebase is relatively small.

The first sensor unit according to one embodiment of the invention mayfurther include a plurality of leads each having one end provided on thebase, and arranged along the first side or the second side, or arrangedalong both of the first side and the second side. In this case, theplurality of leads may be arranged along the first side. Moreover, aplurality of second sensors may be further included that are provided onthe base and arranged on a second axis, in which the second axis issubstantially parallel to the second side and passes through the centerposition of the base. In this case, one of the first sensors and one ofthe second sensors each may be a center position sensor provided at thecenter position of the base, the same number of the remaining firstsensors, excluding the center position sensor, of the first sensors maybe provided on either side of the center position sensor to interposethe center position sensor, and the same number of the remaining secondsensors, excluding the center position sensor, of the second sensors maybe provided on either side of the center position sensor to interposethe center position sensor. In addition, the first sensors may bedisposed on the first axis with a first distance provided therebetweenthat separates the first sensors mutually, and the second sensors may bedisposed on the second axis with a second distance provided therebetweenthat separates the second sensors mutually. In this case, desirably, thefirst distance and the second distance may be substantially equal toeach other.

In the first sensor unit according to one embodiment of the invention,one of the first sensors may be a center position sensor provided at thecenter position of the base, and the same number of the remaining firstsensors, excluding the center position sensor, of the first sensors maybe provided on either side of the center position sensor to interposethe center position sensor. The first sensors may be disposed, forexample, on the first axis with a first distance provided therebetweenthat separates the first sensors mutually.

In the first sensor unit according to one embodiment of the invention,the first sensors may have respective planar shapes that aresubstantially equal to each other, sizes, along the first side, of therespective first sensors may be substantially same as each other, andsizes, along the second side, of the respective first sensors may besubstantially same as each other. The first sensors may havesubstantially same configuration as each other.

In the first sensor unit according to one embodiment of the invention,the first sensors may have respective planar shapes that aresubstantially equal to each other, sizes, along the first side, of therespective first sensors may be substantially same as each other, sizes,along the second side, of the respective first sensors may besubstantially same as each other, the second sensors may have respectiveplanar shapes that are substantially equal to each other, sizes, alongthe first side, of the respective second sensors may be substantiallysame as each other, and sizes, along the second side, of the respectivesecond sensors may be substantially same as each other. In this case,the sizes, along the first side, of the respective first sensors and thesizes, along the first side, of the respective second sensors may besubstantially same as each other, and the sizes, along the second side,of the respective first sensors and the sizes, along the second side, ofthe respective second sensors may be substantially same as each other.The first sensors may have substantially same configuration as eachother, and the second sensors may have substantially same configurationas each other. The configurations of the respective first sensors andthe configurations of the respective second sensors may be substantiallysame as each other.

In the first sensor unit according to one embodiment of the invention,the first sensors and the second sensors each may include amagneto-resistive effect device. In addition, a length of the first sideand a length of the second side may be substantially equal to eachother. The base may have a substrate and a circuit chip stacked on thesubstrate, and a center position of the substrate may be coincident witha center position of the circuit chip.

A second sensor unit according to one embodiment of the inventionincludes a base including a sensor region and n-number of sensors (wheren is an integer equal to or greater than 2). The sensor region has aratio of a size in a second direction to a size in a first directionwhich is less than n, and has a substantially-rectangular planar shape.The n-number of sensors are arrayed in the sensor region in line in thesecond direction, and each have a substantially-rectangular planarshape.

In the second sensor unit according to one embodiment of the invention,the n-number of sensors are arrayed in the sensor region in line in thesecond direction. The sensor region has the ratio of the size in thesecond direction to the size in the first direction which is less thann, and has the substantially-rectangular planar shape. Thus, all of then-number of sensors are placed at respective positions in which adistortion of the base is relatively small, as compared with a casewhere the n-number of sensors are placed in a sensor region in which aratio of a size in the second direction to a size in the first directionis equal to or greater than n.

In the second sensor unit according to one embodiment of the invention,the n-number of sensors each may have a first sensor size in the firstdirection and a second sensor size in the second direction, and thefirst sensor size may be larger than the second sensor size. This caseis preferable in that the planar shape of the sensor region in which then-number of sensors are arrayed becomes closer to square. In addition,the n-number of sensors may be arrayed at substantially even intervals.

In the second sensor unit according to one embodiment of the invention,all of the n-number of sensors may have substantially the same planarshape as each other and may have substantially same occupancy area aseach other.

In the second sensor unit according to one embodiment of the invention,a center position in the second direction of the base and a centerposition in the second direction of the sensor region may be coincidentwith each other.

In the second sensor unit according to one embodiment of the invention,all of the n-number of sensors may have substantially same configurationas each other. For example, the n-number of sensors each may include amagneto-resistive effect device.

In the second sensor unit according to one embodiment of the invention,the base may have a first base size in the first direction and a secondbase size in the second direction, in which the second base size issubstantially equal to the first base size.

In the second sensor unit according to one embodiment of the invention,the base may have a substrate and a circuit chip stacked on thesubstrate, and a center position of the substrate may be coincident witha center position of the circuit chip.

The first sensor unit according to one embodiment of the inventionmitigates stress applied to the first sensors due to a distortion of thebase, making it possible to stabilize outputs of the first sensors. Thesecond sensor unit according to one embodiment of the inventionmitigates stress applied to the n-number of sensors due to a distortionof the base, making it possible to stabilize outputs of the n-number ofsensors. Hence, it is possible to achieve high reliability.

It is to be noted that an effect of the invention is not limitedthereto, and may be any of effects to be described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an overall configuration of a sensor unitaccording to a first embodiment of the invention.

FIG. 2 is a cross-sectional view of a cross-sectional configuration ofthe sensor unit illustrated in FIG. 1.

FIG. 3 is a circuit diagram of the sensor unit illustrated in FIG. 1.

FIG. 4 is a perspective view of a configuration of a sensor illustratedin FIG. 1.

FIG. 5 is a characteristic diagram schematically illustrating changes inoutputs of the sensor illustrated in FIG. 1.

FIG. 6 is a schematic exploded perspective view of a major configurationof a magneto-resistive effect device illustrated in FIG. 3.

FIG. 7 is a plan view of an overall configuration of a sensor unitaccording to a first modification example of the first embodiment.

FIG. 8 is a plan view of an overall configuration of a sensor unitaccording to a second modification example of the first embodiment.

FIG. 9 is a plan view of an overall configuration of a sensor unitaccording to a third modification example of the first embodiment.

FIG. 10 is a plan view of an overall configuration of a sensor unitaccording to a fourth modification example of the first embodiment.

FIG. 11 is a plan view of an overall configuration of a sensor unitaccording to a fifth modification example of the first embodiment.

FIG. 12 is a plan view of an overall configuration of a sensor unitaccording to a sixth modification example of the first embodiment.

FIG. 13 is a plan view of an overall configuration of a sensor unitaccording to a seventh modification example of the first embodiment.

FIG. 14 is a plan view of an overall configuration of a sensor unitaccording to a second embodiment of the invention.

FIG. 15 is a plan view of an overall configuration of a sensor unitaccording to a first modification example of the second embodiment.

FIG. 16 is a plan view of an overall configuration of a sensor unitaccording to a first reference example.

FIG. 17 is a plan view of an overall configuration of a sensor unitaccording to a second reference example.

FIG. 18 is a plan view of an overall configuration of a sensor unitaccording to a third reference example.

FIG. 19 is a characteristic diagram illustrating characteristic valuesof sensors according to a first experimental example.

FIG. 20 is a plan view of an overall configuration of a sensor unitaccording to a third embodiment of the invention.

FIG. 21 is a plan view of an overall configuration of a sensor unitaccording to a first modification example of the third embodiment.

FIG. 22 is a plan view of an overall configuration of a sensor unitaccording to a second modification example of the third embodiment.

FIG. 23 is a plan view of an overall configuration of a sensor unitaccording to a third modification example of the third embodiment.

FIG. 24 is a plan view of an overall configuration of a sensor unitaccording to a fourth embodiment of the invention.

FIG. 25 is a plan view of an overall configuration of a sensor unitaccording to a first modification example of the fourth embodiment.

FIG. 26 is a characteristic diagram illustrating characteristic valuesof sensors according to a second experimental example.

FIG. 27 is a plan view of an overall configuration of a sensor unitaccording to a fourth reference example.

FIG. 28 is a plan view of an overall configuration of a sensor unitaccording to a fifth reference example.

FIG. 29 is a plan view of an overall configuration of a sensor unitaccording to a sixth reference example.

FIG. 30 is a plan view of an overall configuration of a sensor unitaccording to a seventh reference example.

FIG. 31 is a plan view of an overall configuration of a sensor unitaccording to an eighth reference example.

FIG. 32 is a plan view of an overall configuration of a sensor unitaccording to a ninth reference example.

DETAILED DESCRIPTION

In the following, an embodiment of the invention is described in detailwith reference to the drawings. Each drawing is schematic and is notnecessarily drawn strictly. Configurations substantially the same ineach drawing are denoted with the same reference signs, and anyduplicative description is omitted or simplified. Note that thedescription is given in the following order.

1. First Embodiment and its Modification Examples

Examples of a sensor unit in which a center position of a base and acenter position of an IC chip are brought into coincidence with eachother.

2. Second Embodiment and its Modification Example

An example of a sensor unit in which the center position of the base andthe center position of the IC chip are made different from each other.

3. First Experimental Example

4. Third Embodiment and its Modification Examples

Examples of another sensor unit in which the center position of the baseand the center position of the IC chip are brought into coincidence witheach other.

5. Fourth Embodiment and its Modification Example

An example of another sensor unit in which the center position of thebase and the center position of the IC chip are made different from eachother.

6. Second Experimental Example

7. Other Modification Examples

1. First Embodiment

[Configuration of Sensor Unit 1A]

First, a description is given, with reference to FIGS. 1 to 3, of aconfiguration of a sensor unit 1A according to a first embodiment of theinvention. FIG. 1 is a plan view of an example of an overallconfiguration of the sensor unit 1A. FIG. 2 illustrates a cross-sectionof the sensor unit 1A taken along a first axis J1 illustrated in FIG. 1.FIG. 3 is a circuit diagram illustrating a schematic configuration ofthe sensor unit 1A. The sensor unit 1A is used as an angle detectionsensor used for detection of a rotation angle of a rotating body, forexample.

The sensor unit 1A includes a substrate 10, an integrated circuit (IC)chip 20 stacked on the substrate 10, a sensor group 30 stacked on the ICchip 20, and a plurality of leads 40. Note that a combination of thesubstrate 10 and the IC chip 20 is one specific example of a “base”according to the invention.

The substrate 10 has a substantially-rectangular planar shape includinga first side 11 and a second side 12 that are substantially orthogonalto each other. Here, a length of the first side 11 and a length of thesecond side 12 may be substantially equal to each other and the planarshape of the substrate 10 may be substantially square. The term“substantially” means to tolerate a displacement of a level whichresults from a factor such as a manufacturing error. Note that, herein,a direction in which the first side 11 extends is defined as an X-axisdirection, a direction in which the second side 12 extends is defined asa Y-axis direction, and a thickness direction of the substrate 10 (adirection perpendicular to the plane of drawing of FIG. 1) is defined asa Z-axis direction. Further, in FIG. 1, a center position of thesubstrate 10, i.e., an intersection of a second axis J2 that passesthrough a center position in the X-axis direction of the substrate 10and a first axis J1 that passes through a center position in the Y-axisdirection of the substrate 10, is denoted with a reference sign 10J. Inthe present embodiment, the plurality of leads 40 each have one endprovided on the substrate 10, and are arranged along the first side 11.

The IC chip 20 has a rectangular planar shape, and has occupancy areathat is smaller than the substrate 10. In the sensor unit 1A, a centerposition 20J of the IC chip 20, i.e., an intersection of a line thatpasses through a center position in the X-axis direction of the IC chip20 and a line that passes through a center position in the Y-axisdirection of the IC chip 20, is substantially coincident with the centerposition 10J of the substrate 10. Note that the wording “the centerposition 20J and the center position 10J are coincident with each other”means to tolerate a displacement in a range of about ±30 μm whichresults from a factor such as a manufacturing error. In addition, the ICchip 20 includes an arithmetic circuit 21 (see FIG. 3).

The sensor group 30 has sensors 31 to 33 arranged on the first axis J1that passes through the center position 10J (20J) and that is parallelto an X axis, for example. The sensors 31 to 33 each have a rectangularplanar shape, and each have occupancy area that is smaller than the ICchip 20. In addition, the sensor 32 is a center position sensor providedat the center position 10J (20J).

The sensors 31 to 33 are each rectangular in planar shape, and each havea size smaller than a size of the IC chip 20. The planar shape of eachof the sensors 31 to 33 may be square. The sensors 31 to 33 includetheir respective magneto-resistive effect (MR) devices havingconfigurations that are substantially the same as each other, forexample. It is desirable that a distance D312 between the sensor 31 andthe sensor 32 on the first axis J1 be substantially equal to a distanceD323 between the sensor 32 and the sensor 33 on the first axis J1.Accordingly, the sensor 31 and the sensor 33 are so provided as to besymmetric with respect to a line and a point around the sensor 32 thatserves as the center position sensor.

The sensors 31 to 33 each have two sensor sections that outputrespective signals that are different in phase by, e.g., 90 degrees fromeach other with respect to a change (rotation) of an external magneticfield that serves as a detection target. Specifically, for example, thesensors 31 to 33 each have a magnetic sensor section 41 and a magneticsensor section 42 as illustrated in FIG. 4. Note that FIG. 4 is aperspective view of a configuration of any of the sensors 31 to 33. Themagnetic sensor section 41 detects a change (rotation) of an externalmagnetic field H, and outputs a differential signal S1 to the arithmeticcircuit 21 (FIG. 3). Similarly, the magnetic sensor section 42 detectsthe change (rotation) of the external magnetic field H, and outputs adifferential signal S2 to the arithmetic circuit 21 (FIG. 3). However,the phase of the differential signal S1 and the phase of thedifferential signal S2 are different from each other by 90 degrees. Forexample, where the differential signal S1 represents a change in output(for example, a resistance value) based on sine, with respect to arotation angle θ of the external magnetic field H, the differentialsignal S2 represents a change in output (for example, a resistancevalue) based on cos θ with respect to the rotation angle θ of theexternal magnetic field H as illustrated in FIG. 5. FIG. 5 is acharacteristic diagram schematically illustrating the changes in outputswith respect to the rotation angle θ of the external magnetic field H.

As illustrated in FIG. 3, the magnetic sensor section 41 includes abridge circuit 411 in which four magneto-resistive effect (MR:Magneto-Resistive effect) devices 41A to 41D are bridge-connected, and adifference detector 412. Similarly, the magnetic sensor section 42includes a bridge circuit 421 in which four MR devices 42A to 42D arebridge-connected, and a difference detector 422. In the bridge circuit411, one end of the MR device 41A and one end of the MR device 41B arecoupled to each other at a node P1, one end of the MR device 41C and oneend of the MR device 41D are coupled to each other at a node P2, theother end of the MR device 41A and the other end of the MR device 41Dare coupled to each other at a node P3, and the other end of the MRdevice 41B and the other end of the MR device 41C are coupled to eachother at a node P4. Here, the node P3 is coupled to a power source Vcc,and the node P4 is grounded. The nodes P1 and P2 are coupled torespective input terminals of the difference detector 412. Thedifference detector 412 detects a difference in electric potentialbetween the node P1 and the node P2 upon application of a voltagebetween the node P3 and the node P4 (a difference between a voltage dropthat occurs in the MR device 41A and a voltage drop that occurs in theMR device 41D), and outputs the difference to the arithmetic circuit 21as the differential signal S1. Similarly, in the bridge circuit 421, oneend of the MR device 42A and one end of the MR device 42B are coupled toeach other at a node P5, one end of the MR device 42C and one end of theMR device 42D are coupled to each other at a node P6, the other end ofthe MR device 42A and the other end of the MR device 42D are coupled toeach other at a node P7, and the other end of the MR device 42B and theother end of the MR device 42C are coupled to each other at a node P8.Here, the node P7 is coupled to the power source Vcc, and the node P8 isgrounded. The nodes P5 and P6 are coupled to respective input terminalsof the difference detector 422. The difference detector 422 detects adifference in electric potential between the node P5 and the node P6upon application of a voltage between the node P7 and the node P8 (adifference between a voltage drop that occurs in the MR device 42A and avoltage drop that occurs in the MR device 42D), and outputs thedifference to the arithmetic circuit 21 as the differential signal S2.Note that an arrow denoted by a reference sign JSS1 in FIG. 3schematically indicates an orientation of magnetization of amagnetization pinned layer SS1 (to be described later) in each of the MRdevices 41A to 41D and 42A to 42D. In other words, the arrows indicatethat the resistance values of the respective MR devices 41A and 41Cchange in orientations that are same as each other (increase ordecrease) in response to the change in the external magnetic field H,and that the resistance values of the respective MR devices 41B and 41Dboth change in orientations opposite to those of the MR devices 41A and41C (decrease or increase) in response to the change in the externalmagnetic field H. Further, the change in the resistance value of each ofthe MR devices 42A and 42C is shifted in phase by 90 degrees from thechange in the resistance value of each of the MR devices 41A to 41D inresponse to the change in the external magnetic field H. The resistancevalues of the respective MR devices 42B and 42D both change inorientations opposite to those of the MR devices 42A and 42C in responseto the change in the external magnetic field H. Accordingly, forexample, there is a relationship by which a behavior is exhibited inwhich the resistance values of the MR devices 41A and 41C increasewhereas the resistance values of the MR devices 41B and 41D decreasewithin a certain angle range when the external magnetic field H rotatesin a direction of θ (FIG. 4). At that time, the resistance values of theMR devices 42A and 42C change with their phase delayed (or leading) by,e.g., 90 degrees with respect to the change in the resistance values ofthe MR devices 41A and 41C, whereas the resistance values of the MRdevices 42B and 42D change with their phase delayed (or leading) by 90degrees with respect to the change in the resistance values of the MRdevices 41B and 41D.

The MR devices 41A to 41D and 42A to 42D each have a spin-valvestructure in which a plurality of functional films including a magneticlayer are stacked as illustrated in FIG. 6, for example. Specifically,the MR devices 41A to 41D and 42A to 42D each include the magnetizationpinned layer SS1, an intermediate layer SS2, and a magnetization freelayer SS3 that are stacked in order in the Z-axis direction. Themagnetization pinned layer SS1 has the magnetization JSS1 pinned in acertain direction, the intermediate layer SS2 exhibits no magnetizationin specific directions, and the magnetization free layer SS3 has amagnetization J553 that changes in accordance with a density of amagnetic flux of the external magnetic field H. The magnetization pinnedlayer SS1, the intermediate layer SS2, and the magnetization free layerSS3 are each a thin film that spreads in an X-Y plane. Accordingly, anorientation of the magnetization J553 of the magnetization free layerSS3 is rotatable in the X-Y plane. Note that FIG. 6 illustrates a loadstate in which the external magnetic field H is given in the orientationof the magnetization J553. Further, the magnetization pinned layer SS1in each of the MR devices 41A and 41C has the magnetization JSS1 pinnedin a +X direction, for example, and the magnetization pinned layer SS1in each of the MR devices 41B and 41D has the magnetization JSS1 pinnedin a −X direction. Note that the magnetization pinned layer SS1, theintermediate layer SS2, and the magnetization free layer SS3 each mayhave either a single-layer structure or a multi-layer structureincluding a plurality of layers. Further, the magnetization pinned layerSS1, the intermediate layer SS2, and the magnetization free layer SS3may be stacked in order reverse to that described above.

The magnetization pinned layer SS1 is made of a ferromagnetic materialsuch as cobalt (Co), a cobalt-iron alloy (CoFe), and a cobalt-iron-boronalloy (CoFeB). Note that an antiferromagnetic layer (not illustrated)may be so provided on the opposite side of the intermediate layer SS2 asto be adjacent to the magnetization pinned layer SS1. Such anantiferromagnetic layer is made of an antiferromagnetic material such asa platinum-manganese alloy (PtMn) and an iridium-manganese alloy (IrMn).For example, in the magnetic sensor section 41, the antiferromagneticlayer is in a state in which a spin magnetic moment in the +X directionand a spin magnetic moment in the −X direction completely cancel eachother, and serves to fix the orientation of the magnetization JSS1 ofthe adjacent magnetization pinned layer SS1 in the +X direction.

In a case where the spin-valve structure functions as a magnetic tunneljunction (MTJ: Magnetic Tunnel Junction) film, the intermediate layerSS2 is a non-magnetic tunnel barrier layer made of a magnesium oxide(MgO), for example, and has a thickness that is thin to the extent thata tunnel current based on quantum mechanics is able to passtherethrough. The tunnel barrier layer made of MgO is obtained by aprocess such as a process of oxidizing a thin film made of magnesium(Mg) and a reactive sputtering process in which sputtering of magnesiumis performed under an oxygen atmosphere, besides a sputtering processthat uses a target made of MgO, for example. It is also possible toconfigure the intermediate layer SS2 with use of an oxide or a nitrideof each of aluminum (Al), tantalum (Ta), and hafnium (Hf), besides MgO.Note that the intermediate layer SS2 may be configured by an element ofthe platinum group such as ruthenium (Ru), or a non-magnetic metal suchas copper (Cu) and gold (Au), for example. In this case, the spin-valvestructure functions as a giant magneto resistive effect (GMR: GiantMagneto Resistive effect) film.

The magnetization free layer SS3 is a soft ferromagnetic layer, andconfigured by a cobalt-iron alloy (CoFe), a nickel-iron alloy (NiFe), acobalt-iron-boron alloy (CoFeB), or the like, for example.

The MR devices 41A to 41D configuring the bridge circuit 411 are eachsupplied with a current I1 or a current I2 in each of which a currentI10 supplied from the power source Vcc is divided at the node P3.Signals e1 and e2 outputted from the respective nodes P1 and P2 of thebridge circuit 411 are supplied into the difference detector 412. Here,where an angle between the magnetization JSS1 and the magnetization J553is defined as γ, for example, the signal e1 represents an output changethat changes in accordance with A cos(+γ)+B, and the signal e2represents an output change that changes in accordance with Acos(γ−180°)+B (A and B are each a constant).

On the other hand, the MR devices 42A to 42D configuring the bridgecircuit 421 are each supplied with a current I3 or a current I4 in eachof which the current I10 supplied from the power source Vcc is dividedat the node P7. Signals e3 and e4 outputted from the respective nodes P5and P6 of the bridge circuit 421 are supplied into the differencedetector 422. Here, the signal e3 represents an output change thatchanges in accordance with A sin(+γ)+B, and the signal e4 represents anoutput change that changes in accordance with A sin(γ−180°)+B. Further,the differential signal S1 from the difference detector 412 and thedifferential signal S2 from the difference detector 422 are suppliedinto the arithmetic circuit 21. The arithmetic circuit 21 calculates anangle based on tan γ. Here, γ is equivalent to the rotation angle θ ofthe external magnetic field H relative to the sensor group 30, thusmaking it possible to determine the rotation angle θ.

[Operation and Workings of Sensor Unit 1A]

The sensor unit 1A according to the present embodiment makes it possibleto detect, by means of the sensor group 30, a magnitude of the rotationangle θ of the external magnetic field H in the X-Y plane, for example.

In the sensor unit 1A, when the external magnetic field H rotatesrelative to the sensor group 30, a change in magnetic field component inthe X-axis direction and a change in magnetic field component in theY-axis direction, both reaching the sensor group 30, are detected by theMR devices 41A to 41D in the magnetic sensor section 41 and the MRdevices 42A to 42D in the magnetic sensor section 42. At that time, thedifferential signals S1 and S2 that represent the changes illustrated inFIG. 5, for example, are supplied into the arithmetic circuit 21 asoutputs from the respective bridge circuits 411 and 421. Thereafter, itis possible to determine the rotation angle θ of the external magneticfield H by the arithmetic circuit 21 on the basis of the expression:Arctan(α sin θ/(β cos θ).

[Effect of Sensor Unit 1A]

According to the sensor unit 1A, characteristics of the detection on theexternal magnetic field H are improved in the sensors 31 to 33 that areincluded in the sensor group 30.

Specifically, a decrease in orthogonality (orthogonality) is suppressedin each of the sensors 31 to 33 even in a case where a change intemperature occurs. The term “orthogonality” as used herein refers to anamount of shift, from a set value (e.g., 90 degrees), of the phase ofthe output (the differential signal S2) outputted by the magnetic sensorsection 42 relative to the phase of the output (the differential signalS1) outputted by the magnetic sensor section 41, for example. The closerthe amount of shift is to zero, the more preferable the amount of shiftis.

A reason that the decrease in orthogonality of the sensors 31 to 33 issuppressed in the sensor unit 1A according to the present embodiment ispresumably due to placement of each of the sensors 31 to 33 at aposition at which a distortion of the substrate 10 caused by the changein temperature is relatively small. In other words, the plurality ofsensors 31 to 33 are presumably less susceptible to the distortion ofthe substrate 10 owing to arrangement of the plurality of sensors 31 to33 on the first axis J1, of the substrate 10 having thesubstantially-rectangular planar shape, that is substantially parallelto the first side 11 and passes through the center position 10J. Notethat causes of the change in temperature include heat generation of theIC chip 20, besides a change in temperature of a surroundingenvironment.

In particular, in the sensor unit 1A according to the presentembodiment, the plurality of sensors 31 to 33 are arranged in adirection (here, the X-axis direction) that coincides with a directionin which the plurality of leads 40 are arranged, thus making it possibleto further mitigate the stress to be applied to each of the sensors 31to 33. A reason is that it is possible to allow a distance in the Y-axisdirection between the sensors 31 to 33 and respective connection pointsat which the plurality of leads 40 and the substrate 10 are connected tobe substantially constant. Hence, it is possible to avoid the decreasein orthogonality of the sensors 31 to 33.

First Modification Example of First Embodiment (Modification Example1-1)

FIG. 7 is a plan view of an example of an overall configuration of asensor unit 1B according to a first modification example (modificationexample 1-1) of the present embodiment. In the sensor unit 1A accordingto the foregoing first embodiment, the plurality of sensors 31 to 33 arearranged on the first axis J1 that is substantially parallel to thedirection in which the plurality of leads 40 are arranged (the X-axisdirection). In contrast, according to the present modification example,a plurality of sensors 34, 32, and 35 are arranged in order on a secondaxis J2 that is substantially orthogonal to the direction in which theplurality of leads 40 are arranged (the X-axis direction) and passesthrough the center position 10J (20J). Here, the sensor 34 and thesensor 35 may be so disposed as to be symmetric with respect to a lineand a point around the sensor 32. In other words, it is desirable that adistance D342 between the sensor 34 and the sensor 32 and a distanceD325 between the sensor 32 and the sensor 35 be substantially equal toeach other. Disposing the sensors 34, 32, and 35 in this manner alsomakes it possible to avoid the decrease in orthogonality of the sensors34, 32, and 35.

Second Modification Example of First Embodiment (Modification Example1-2)

FIG. 8 is a plan view of an example of an overall configuration of asensor unit 1C according to a second modification example (modificationexample 1-2) of the present embodiment. According to the presentmodification example, the plurality of sensors are arranged on both ofthe first axis J1 and the second axis J2. Specifically, the sensors 31,32, and 33 are so configured as to be arranged on the first axis J1 andthe sensors 34, 32, and 35 are so configured as to be arranged on thesecond axis J2. The sensors 31 to 35 may be disposed at respectivepositions that are rotational symmetric about the center position 10J(20J). Disposing the sensors 31 to 35 in this manner also makes itpossible to avoid the decrease in orthogonality of the sensors 31 to 35.

Third Modification Example of First Embodiment (Modification Example1-3)

FIG. 9 is a plan view of an example of an overall configuration of asensor unit 1D according to a third modification example (modificationexample 1-3) of the present embodiment. In the sensor unit 1A accordingto the foregoing first embodiment, the plurality of sensors 31 to 33each have a square planar shape. In contrast, according to the presentmodification example, the sensors 31 to 33 are each so configured that,as compared with a size in the direction in which the sensors 31 to 33are arranged (the X-axis direction), a size in a direction orthogonal tothe arrangement direction thereof (the Y-axis direction) becomes large.Allowing each of the sensors 31 to 33 to have such as shape (arectangle) also makes it possible to avoid the decrease in orthogonalityand to avoid a decrease in amplitude ratio as well. The term “amplituderatio” as used herein refers to a ratio of amplitude of the output fromthe magnetic sensor section 42 (the differential signal S2) to amplitudeof the output from the magnetic sensor section 41 (the differentialsignal S1), for example. The closer the amplitude ratio is to one, themore preferable the amplitude ratio is.

Fourth Modification Example of First Embodiment (Modification Example1-4)

FIG. 10 is a plan view of an example of an overall configuration of asensor unit 1E according to a fourth modification example (modificationexample 1-4) of the present embodiment. According to the presentmodification example, the sensors 34, 32, and 35 are so configured as tobe arranged on the second axis J2, and the sensors 34, 32, and 35 areeach so configured that, as compared with the size in the direction inwhich the sensors 34, 32, and 35 are arranged (the Y-axis direction),the size in the direction orthogonal to the arrangement directionthereof (the X-axis direction) becomes large. It is also possible forthe present modification example to avoid the decrease in orthogonalityof the sensors 34, 32, and 35 and to avoid the decrease in amplituderatio as well.

Fifth Modification Example of First Embodiment (Modification Example1-5)

FIG. 11 is a plan view of an example of an overall configuration of asensor unit 1F according to a fifth modification example (modificationexample 1-5) of the present embodiment. According to the presentmodification example, even number of sensors 51 to 54 are arranged onthe first axis J1. In the present modification example, the sensor 51and the sensor 54 may be disposed symmetrically and the sensor 52 andthe sensor 53 may be disposed symmetrically, both with respect to thesecond axis J2 as an axis of symmetry. Disposing the sensors 51 to 54 inthis manner also makes it possible to avoid the decrease inorthogonality of the sensors 51 to 54.

Sixth Modification Example of First Embodiment (Modification Example1-6)

FIG. 12 is a plan view of an example of an overall configuration of asensor unit 1G according to a sixth modification example (modificationexample 1-6) of the present embodiment. According to the presentmodification example, even number of sensors 55 to 58 are arranged onthe second axis J2. In the present modification example, the sensor 55and the sensor 58 may be disposed symmetrically and the sensor 56 andthe sensor 57 may be disposed symmetrically, both with respect to thefirst axis J1 as the axis of symmetry. Disposing the sensors 55 to 58 inthis manner also makes it possible to avoid the decrease inorthogonality of the sensors 55 to 58.

Seventh Modification Example of First Embodiment (Modification Example1-7)

FIG. 13 is a plan view of an example of an overall configuration of asensor unit 1H according to a seventh modification example (modificationexample 1-7) of the present embodiment. According to the presentmodification example, the plurality of sensors are arranged on both ofthe first axis J1 and the second axis J2. Specifically, the sensors 31and 33 are so configured as to be arranged on the first axis J1 and thesensors 34 and 35 are so configured as to be arranged on the second axisJ2. The sensors 31, 33, 34, and 35 may be disposed at respectivepositions that are rotational symmetric about the center position 10J(20J). Disposing the sensors 31, 33, 34, and 35 in this manner alsomakes it possible to avoid the decrease in orthogonality of the sensors31, 33, 34, and 35.

2. Second Embodiment

[Configuration of Sensor Unit 2A]

FIG. 14 is a plan view of an example of an overall configuration of asensor unit 2A according to a second embodiment of the invention. Thesensor units 1A and 1B according to the foregoing first embodiment areeach so configured that the center position 20J of the IC chip 20 andthe center position 10J of the substrate 10 are brought into coincidencewith each other substantially. In contrast, the sensor unit 2A accordingto the present embodiment is so configured that the center position 20Jof the IC chip 20 and the center position 10J of the substrate 10 aremade different from each other. Specifically, the center position 20J ofthe IC chip 20 is located at a position moved in the +X direction fromthe center position 10J of the substrate 10. Further, the sensors 31 to33 are so disposed as to be arranged on a third axis J3 that isorthogonal to the first axis J1 and passes through the center position20J of the IC chip 20.

It is also possible for the sensor unit 2A according to the presentembodiment to avoid the decrease in orthogonality of the sensors 31 to33.

Modification Example of Second Embodiment (Modification Example 2-1)

FIG. 15 is a plan view of an example of an overall configuration of asensor unit 2B according to a first modification example (modificationexample 2-1) of the present embodiment. The present modification examplehas a configuration similar to that of the foregoing sensor unit 2A,with exception that the sensors 34, 32, and 35 are arranged in order onthe second axis J2. Disposing the sensors 34, 32, and 35 in this manneralso makes it possible to avoid the decrease in orthogonality of thesensors 34, 32, and 35.

3. First Experimental Example

Samples were fabricated of the respective sensor units 1A to 1H, 2A, and2B referred to in the foregoing first and second embodiments and theirmodification examples to measure the amplitude ratio (%) and theorthogonality (deg) of each of them. Here, experimental example 1Acorresponds to the sensor unit 1A of FIG. 1, experimental example 1Bcorresponds to the sensor unit 1B of FIG. 7, experimental example 1Ccorresponds to the sensor unit 1C of FIG. 8, experimental example 1Dcorresponds to the sensor unit 1D of FIG. 9, experimental example 1Ecorresponds to the sensor unit 1E of FIG. 10, experimental example 1Fcorresponds to the sensor unit 1F of FIG. 11, experimental example 1Gcorresponds to the sensor unit 1G of FIG. 12, experimental example 1Hcorresponds to the sensor unit 1H of FIG. 13, experimental example 2Acorresponds to the sensor unit 2A of FIG. 14, and experimental example2B corresponds to the sensor unit 2B of FIG. 15.

Further, experimental example 3A corresponds to a sensor unit 3Aaccording to a reference example illustrated in FIG. 16, experimentalexample 3B corresponds to a sensor unit 3B according to a referenceexample illustrated in FIG. 17, and experimental example 3C correspondsto a sensor unit 3C according to a reference example illustrated in FIG.18. The sensor unit 3A of FIG. 16 includes a sensor group 130 havingsensors 131 to 133 that are arranged in the X-axis direction atrespective positions off the first axis J1. The sensor unit 3B of FIG.17 includes a sensor group 130A having sensors 134, 132, and 135 thatare arranged in the Y-axis direction at respective positions off thesecond axis J2. The sensor unit 3C of FIG. 18 includes the sensor group130 having the sensors 131 to 133 that are arranged in a directionoblique to both the first axis J1 and the second axis J2.

FIG. 19 illustrates a relationship of the orthogonality versus adifference between amplitude ratio before heating of a substrate andamplitude ratio after the heating of the substrate (hereinafter simplyreferred to as an amplitude ratio difference), for each of the samples.As used herein, the wording “the amplitude ratio after the heating ofthe substrate” refers to the amplitude ratio measured immediately aftercausing the substrate 10 to be held at a temperature of 120 degreescentigrade for 24 hours. The amplitude ratio before the heating of thesubstrate is the amplitude ratio measured at a room temperature (23degrees centigrade). The closer the amplitude ratio difference is tozero, the more preferable the amplitude ratio difference is. It is mostpreferable that the amplitude ratio difference be substantially zero. InFIG. 19, a horizontal axis denotes the orthogonality [deg] whereas avertical axis denotes the amplitude ratio difference [%]. Note thatplots corresponding to the respective experimental examples 1A to 3C aredenoted with their respective reference signs PL1A to PL3C in FIG. 19.FIG. 19 illustrates data that corresponds to a sensor located at asurrounding part of any of the samples. Specifically, in FIG. 19, theexperimental example 1A (FIG. 1) illustrates data corresponding to thesensor 33, the experimental example 1B (FIG. 7) illustrates datacorresponding to the sensor 35, the experimental example 1C (FIG. 8)illustrates data corresponding to the sensor 33, the experimentalexample 1D (FIG. 9) illustrates data corresponding to the sensor 33, theexperimental example 1E (FIG. 10) illustrates data corresponding to thesensor 35, the experimental example 1F (FIG. 11) illustrates datacorresponding to the sensor 54, the experimental example 1G (FIG. 12)illustrates data corresponding to the sensor 58, the experimentalexample 1H (FIG. 13) illustrates data corresponding to the sensor 33,the experimental example 2A (FIG. 14) illustrates data corresponding tothe sensor 35, the experimental example 2B (FIG. 15) illustrates datacorresponding to the sensor 35, the experimental example 3A (FIG. 16)illustrates data corresponding to the sensor 133, the experimentalexample 3B (FIG. 17) illustrates data corresponding to the sensor 135,and the experimental example 3C (FIG. 18) illustrates data correspondingto the sensor 133.

As illustrated in FIG. 19, degradation of the orthogonality was observedfor the experimental examples 3A to 3C (the plots PL3A to PL3C)according to the reference examples. However, relatively fineorthogonality was obtained for the rest of the experimental examples.Among them, better amplitude ratio was obtained for the experimentalexamples 1A and 1B (FIG. 1 and FIG. 7), and even better amplitude ratiowas obtained for the experimental examples 1D, 1E, and 1H (FIG. 9, FIG.10, and FIG. 13).

4. Third Embodiment

[Configuration of Sensor Unit 101A]

First, a description is given, with reference to FIG. 20 in addition toFIGS. 2 to 6 according to the first embodiment, of a configuration of asensor unit 101A according to a third embodiment of the invention. FIG.20 is a plan view of an example of an overall configuration of thesensor unit 101A. The foregoing FIG. 2 is equivalent to a cross-sectionof the sensor unit 101A taken along a first axis J101 illustrated inFIG. 20. The foregoing FIG. 3 is equivalent to a circuit diagram thatillustrates a schematic configuration of the sensor unit 101A. Thesensor unit 101A is used as the angle detection sensor used for thedetection of the rotation angle of the rotating body, for example.

The sensor unit 101A includes a substrate 110, an integrated circuit(IC) chip 120 stacked on the substrate 110, a sensor group 130A stackedon the IC chip 120, and a plurality of leads 40. Note that a combinationof the substrate 110 and the IC chip 120 is one specific example of the“base” according to the invention.

The substrate 110 has a substantially-rectangular planar shape includinga first side 111 and a second side 112 that are substantially orthogonalto each other. Here, a length of the first side 111 and a length of thesecond side 112 may be substantially equal to each other and the planarshape of the substrate 110 may be substantially square. The term“substantially” means to tolerate a displacement of a level whichresults from a factor such as a manufacturing error. Note that, herein,a direction in which the first side 111 extends is defined as the X-axisdirection, a direction in which the second side 112 extends is definedas the Y-axis direction, and a thickness direction of the substrate 110(a direction perpendicular to the plane of drawing of FIG. 20) isdefined as the Z-axis direction. Further, in FIG. 20, a center positionof the substrate 110, i.e., an intersection of a second axis J102 thatpasses through a center position in the X-axis direction of thesubstrate 110 and the first axis J101 that passes through a centerposition in the Y-axis direction of the substrate 110, is denoted with areference sign 110J. In the present embodiment, the plurality of leads140 each have one end provided on the substrate 110, and are arrangedalong the first side 111.

The IC chip 120 has a rectangular planar shape, and has occupancy areathat is smaller than the substrate 110. In the sensor unit 101A, acenter position 120J of the IC chip 120, i.e., an intersection of a linethat passes through a center position in the X-axis direction of the ICchip 120 and a line that passes through a center position in the Y-axisdirection of the IC chip 120, is substantially coincident with thecenter position 110J of the substrate 110. Note that the wording “thecenter position 120J and the center position 110J are coincident witheach other” means to tolerate a displacement in a range of about ±30 μmwhich results from a factor such as a manufacturing error. In addition,the IC chip 120 includes the arithmetic circuit 21 (see FIG. 3).

The sensor group 130A has n-number of sensors (three sensors 131 to 133in the present embodiment) arranged on the first axis J101 that passesthrough the center position 110J (120J) and that is parallel to the Xaxis, for example (where n is an integer of 2 or greater). A sensorregion R130A, in which the sensors 131 to 133 are arrayed, on thesubstrate 110 has a size X130A in the X-axis direction and a size Y130Ain the Y-axis direction, and has occupancy area that is smaller than theIC chip 120. Here, a ratio of the size X130A to the size Y130A, i.e., anaspect ratio, is less than n (here, 3). Note that the closer the aspectratio is to one, the more preferable the aspect ratio is. It is mostpreferable that the aspect ratio be substantially one. In addition, thefirst axis J101 that passes through the center position 110J in theY-axis direction of the substrate 110 and an axis J130X that passesthrough a center position in the Y-axis direction of the sensor regionR130A are substantially coincident with each other.

The sensors 131 to 133 are each rectangular in planar shape, and eachhave a size smaller than a size of the IC chip 120. Each of the sensors131 to 133 has the planar shape in which the size in the Y-axisdirection is larger than the size in the X-axis direction. Inparticular, all of the sensors 131 to 133 may have substantially thesame planar shape as each other and may have substantially the sameoccupancy area as each other. The sensors 131 to 133 include theirrespective magneto-resistive effect (MR) devices having configurationsthat are substantially the same as each other, for example. It isdesirable that a distance D1312 between the sensor 131 and the sensor132 on the first axis J101 be substantially equal to a distance D1323between the sensor 132 and the sensor 133 on the first axis J101. Inother words, it is desirable that the n-number of sensors be arrayed atsubstantially even intervals. Accordingly, the sensor 131 and the sensor133 are so provided as to be symmetric with respect to a line and apoint around the sensor 132 that serves as a center position sensorprovided at the center position 110J (120J).

The sensors 131 to 133 have their respective configurations that aresimilar to those of the respective sensors 31 to 33 illustrated in FIG.4.

[Operation and Workings of Sensor Unit 101A]

The sensor unit 101A according to the present embodiment makes itpossible to detect, by means of the sensor group 130A, a magnitude ofthe rotation angle θ of the external magnetic field H in the X-Y plane,for example (see FIG. 4).

In the sensor unit 101A, when the external magnetic field H rotatesrelative to the sensor group 130A, a change in magnetic field componentin the X-axis direction and a change in magnetic field component in theY-axis direction, both reaching the sensor group 130A, are detected bythe MR devices 41A to 41D in the magnetic sensor section 41 and the MRdevices 42A to 42D in the magnetic sensor section 42. At that time, thedifferential signals S1 and S2 that represent the changes illustrated inFIG. 5, for example, are supplied into the arithmetic circuit 21 as theoutputs from the respective bridge circuits 411 and 421. Thereafter, itis possible to determine the rotation angle θ of the external magneticfield H by the arithmetic circuit 21 on the basis of the expression:Arctan(α sin θ/(β cos θ).

[Effect of Sensor Unit 101A]

According to the sensor unit 101A, characteristics of the detection onthe external magnetic field H are improved in the sensors 131 to 133that configure the sensor group 130A.

Specifically, the decrease in orthogonality (orthogonality) issuppressed in each of the sensors 131 to 133 even in a case where thechange in temperature occurs. The term “orthogonality” as used hereinrefers to the amount of shift, from a set value (e.g., 90 degrees), ofthe phase of the output (the differential signal S2) outputted by themagnetic sensor section 42 relative to the phase of the output (thedifferential signal S1) outputted by the magnetic sensor section 41, forexample. The closer the amount of shift is to zero, the more preferablethe amount of shift is.

A reason that the decrease in orthogonality of the sensors 131 to 133 issuppressed in the sensor unit 101A according to the present embodimentis presumably due to placement of each of the sensors 131 to 133 at aposition at which a distortion of the substrate 110 caused by the changein temperature is relatively small. In other words, the plurality ofsensors 131 to 133 are presumably less susceptible to the distortion ofthe substrate 110 owing to arrangement of the plurality of sensors 131to 133 on the first axis J101, of the substrate 110 having thesubstantially-rectangular planar shape, that is substantially parallelto the first side 111 and passes through the center position 110J. Notethat causes of the change in temperature include heat generation of theIC chip 120, besides the change in temperature of the surroundingenvironment.

In particular, in the sensor unit 101A according to the presentembodiment, the plurality of sensors 131 to 133 are arranged in adirection (here, the X-axis direction) that coincides with a directionin which the plurality of leads 140 are arranged, thus making itpossible to further mitigate the stress to be applied to each of thesensors 131 to 133. A reason is that it is possible to allow a distancein the Y-axis direction between the sensors 131 to 133 and respectiveconnection points at which the plurality of leads 140 and the substrate110 are connected to be substantially constant. Hence, it is possible toavoid the decrease in orthogonality of the sensors 131 to 133.

Further, in the sensor unit 101A according to the present embodiment,the n-number of sensors (three sensors 131 to 133) are arrayed in thesensor region R130A, on the substrate 110, in which the ratio of thesize X130A to the size Y130A is less than n. In other words, the planarshape of each of the sensors 131 to 133 is rectangle in which adirection (here, Y-axis direction) orthogonal to the direction in whichthe sensors 131 to 133 are arranged is a longitudinal direction. Thismakes it possible to bring the aspect ratio of the sensor region R130Acloser to one as compared with a case where the planar shape of each ofthe sensors 131 to 133 is square, for example. Hence, it is possible toachieve the improvement in amplitude ratio of each of the sensors 131 to133 as compared with a case where the n-number of sensors are placed ina sensor region whose aspect ratio is n or greater. The term “amplituderatio” as used herein refers to the ratio of amplitude (S2/S1) of theoutput from the magnetic sensor section 42 (the differential signal S2)to amplitude of the output from the magnetic sensor section 41 (thedifferential signal S1), for example. The closer the amplitude ratioS2/S1 is to one, the more preferable the amplitude ratio is. It is mostpreferable that the amplitude ratio S2/S1 be substantially one.

First Modification Example of Third Embodiment (Modification Example3-1)

FIG. 21 is a plan view of an example of an overall configuration of asensor unit 101B according to a first modification example (modificationexample 3-1) of the present embodiment. For the sensor unit 101Aaccording to the foregoing third embodiment, described is a case wheren=3, i.e., a case where the sensor group 130A has the three sensors 131to 133. In contrast, the sensor unit 101B according to the presentmodification example has, instead of the sensor group 130A, a sensorgroup 150B corresponding to n=4, i.e., configured by four sensors 151 to154. Here, the four sensors 151 to 154 are arranged on the first axisJ101, and are arrayed in a sensor region R150B in which the ratio of asize X150B to a size Y150B is less than 4. Thus, it is also possible forthe present modification example to achieve the improvement in theamplitude ratio of the sensors 151 to 154. Note that the first axis J101that passes through the center position 110J of the substrate 110 and anaxis J150X that passes through a center position in the Y-axis directionof the sensor region R150B are substantially coincident with each other.

Second Modification Example of Third Embodiment (Modification Example3-2)

FIG. 22 is a plan view of an example of an overall configuration of asensor unit 101C according to a second modification example(modification example 3-2) of the present embodiment. In the sensor unit101A according to the foregoing third embodiment, the plurality ofsensors 131 to 133 are arranged on the first axis J101 that issubstantially parallel to the direction in which the plurality of leads140 are arranged (the X-axis direction). In contrast, according to thepresent modification example, a plurality of sensors 134, 132, and 135are arranged in order on the second axis J102 that is substantiallyorthogonal to the direction in which the plurality of leads 140 arearranged (the X-axis direction) and passes through the center position110J (120J). In other words, the second axis J102 and an axis J130Y thatpasses through a center position in the X-axis direction of a sensorregion R130C are substantially coincident with each other. The sensors134, 132, and 135 configure a sensor group 130C. Here, the sensor 134and the sensor 135 may be so disposed as to be symmetric with respect toa line and a point around the sensor 132. In other words, it isdesirable that a distance D1342 between the sensor 134 and the sensor132 and a distance D1325 between the sensor 132 and the sensor 135 besubstantially equal to each other. Further, the sensor group 130Cconfigured by the sensors 134, 132, and 135 occupies the sensor region130C in which the ratio of a size Y130C in a longitudinal direction to asize X130C in a transverse direction is less than 3. Disposing thesensors 134, 132, and 135 in this manner also makes it possible toachieve the improvement in the amplitude ratio of the sensors 134, 132,and 135.

Third Modification Example of Third Embodiment (Modification Example3-3)

FIG. 23 is a plan view of an example of an overall configuration of asensor unit 101D according to a third modification example (modificationexample 3-3) of the present embodiment. For the sensor unit 101Caccording to the second modification example of the foregoing thirdembodiment, described is a case where n=3, i.e., a case where the sensorgroup 130C has the three sensors 134, 132, and 135. In contrast, thesensor unit 101D according to the present modification example has,instead of the sensor group 130C, a sensor group 150D corresponding ton=4, i.e., configured by four sensors 155 to 158. Here, the four sensors155 to 158 are arrayed in a sensor region R150D in which the ratio of asize Y150D to a size X150D is less than 4. Thus, it is also possible forthe present modification example to achieve the improvement in theamplitude ratio of the sensors 155 to 158. Note that an axis J150Y thatpasses through a center position in the X-axis direction of the sensorregion R150D is substantially coincident with the second axis J102.

5. Fourth Embodiment

[Configuration of Sensor Unit 102A]

FIG. 24 is a plan view of an example of an overall configuration of asensor unit 102A according to a fourth embodiment of the invention. Thesensor units 101A to 101D according to the foregoing third embodimentare each so configured that the first axis J101 or the second axis J102that passes through the center position 110J of the substrate 110 isbrought into coincidence substantially with the axes J130X and J150Xthat pass through the respective centers of the sensor regions R130A andR150B, or with the axes J130Y and J150Y that pass through the respectivecenters of the sensor regions R130C and R150D. In contrast, the sensorunit 102A according to the present embodiment includes a sensor group130E having the sensors 131 to 133 that are arranged on the axis J130Xthat is parallel to the first axis J101 but is located at a positiondifferent from the first axis J101.

In the sensor unit 102A according to the present embodiment, the threesensors 131 to 133 of the sensor group 130E are arrayed in the sensorregion R130E in which the ratio of the size X130E to the size Y130E isless than 3. This makes it also possible for the sensor unit 102A tobring the aspect ratio of the sensor region R130E closer to one ascompared with the case where the planar shape of each of the sensors 131to 133 is square, for example. Hence, it is possible to achieve theimprovement in the amplitude ratio of each of the sensors 131 to 133.

Modification Example of Fourth Embodiment (Modification Example 4-1)

FIG. 25 is a plan view of an example of an overall configuration of asensor unit 102B according to a first modification example (modificationexample 4-1) of the present embodiment. The present modification exampleincludes a sensor group 130F having the sensors 134, 132, and 135 thatare arranged in order on the axis J130Y that is parallel to the secondaxis J102 but is located at a position different from the second axisJ102. Otherwise, the present modification example has a configurationsimilar to that of the foregoing sensor unit 102A. In other words, inthe sensor unit 102B, the three sensors 134, 132, and 135 of the sensorgroup 130F are arrayed in a sensor region R130F in which the ratio of asize Y130F to a size X130F is less than 3. Disposing the sensors 134,132, and 135 in this manner also makes it possible to achieve theimprovement in the amplitude ratio of the sensors 134, 132, and 135.

6. Second Experimental Example

Samples were fabricated of the respective sensor units 101A to 101D,102A, and 102B referred to in the foregoing third and fourth embodimentsand their modification examples to measure the amplitude ratio (%) andthe orthogonality (deg) of each of them. Here, experimental example 101Acorresponds to the sensor unit 101A of FIG. 20, experimental example101B corresponds to the sensor unit 101B of FIG. 21, experimentalexample 101C corresponds to the sensor unit 101C of FIG. 22,experimental example 101D corresponds to the sensor unit 101D of FIG.23, experimental example 102A corresponds to the sensor unit 102A ofFIG. 24, and experimental example 102B corresponds to the sensor unit102B of FIG. 25. In these experimental examples 101A to 101D, 102A, and102B, the planar shape of the substrate 110 was square of 5.0 mm square,and the planar shape of the IC chip was square of 3.5 mm square.Further, in the experimental examples 101A, 101C, 102A, and 102B, thesensor regions R130A, R130C, R130E, and R130F were each 1.6 mm×0.6 mmrectangle, and the planar shape of each of the sensors 131 to 135 was0.4 mm×0.6 mm rectangle. In the experimental examples 101B and 101D, thesensor regions R150B and R150D were each 2.2 mm×0.6 mm rectangle, andthe planar shape of each of the sensors 151 to 158 was 0.4 mm×0.6 mmrectangle.

Further, experimental example 103A corresponds to a sensor unit 103Aaccording to a reference example illustrated in FIG. 27. The sensor unit103A is similar in configuration to the sensor unit 101A (FIG. 20), withexception that the sensor unit 103A includes, instead of the sensorgroup 130A, a sensor group 1130A having sensors 1131 to 1133. Similarly,experimental example 103B corresponds to a sensor unit 103B according toa reference example illustrated in FIG. 28. The sensor unit 103B issimilar in configuration to the sensor unit 101B (FIG. 21), withexception that the sensor unit 103B includes, instead of the sensorgroup 150B, a sensor group 1150B having sensors 1151 to 1154.Experimental example 103C corresponds to a sensor unit 103C according toa reference example illustrated in FIG. 29. The sensor unit 103C issimilar in configuration to the sensor unit 101C (FIG. 22), withexception that the sensor unit 103C includes, instead of the sensorgroup 130C, a sensor group 1130C having sensors 1132, 1134, and 1135.Experimental example 103D corresponds to a sensor unit 103D according toa reference example illustrated in FIG. 30. The sensor unit 103D issimilar in configuration to the sensor unit 101D (FIG. 23), withexception that the sensor unit 103D includes, instead of the sensorgroup 150D, a sensor group 1150D having sensors 1155 to 1158.Experimental example 104A corresponds to a sensor unit 104A according toa reference example illustrated in FIG. 31. The sensor unit 104A issimilar in configuration to the sensor unit 102A (FIG. 24), withexception that the sensor unit 104A includes, instead of the sensorgroup 130E, a sensor group 1130E having the sensors 1131 to 1133.Experimental example 104B corresponds to a sensor unit 104B according toa reference example illustrated in FIG. 32. The sensor unit 104B issimilar in configuration to the sensor unit 102B (FIG. 25), withexception that the sensor unit 104B includes, instead of the sensorgroup 130F, a sensor group 1130F having the sensors 1132, 1134, and1135. Note that, in the experimental examples 103A, 103C, 104A, and104B, the sensor regions R1130A, R1130C, R1130E, and R1130F were each1.6 mm×0.4 mm rectangle, and the planar shape of each of the sensors1131 to 1135 was 0.4 mm×0.4 mm square. In the experimental examples 103Band 103D, the sensor regions R1150B and R1150D were each 2.2 mm×0.4 mmrectangle, and the planar shape of each of the sensors 1151 to 1158 was0.4 mm×0.4 mm square.

FIG. 26 illustrates a relationship of the orthogonality versus adifference between amplitude ratio before heating of a substrate andamplitude ratio after the heating of the substrate (hereinafter simplyreferred to as an amplitude ratio difference), for each of the samples.As used herein, the wording “the amplitude ratio after the heating ofthe substrate” refers to the amplitude ratio measured immediately aftercausing the substrate 110 to be held at a temperature of 120 degreescentigrade for 24 hours. The amplitude ratio before the heating of thesubstrate is the amplitude ratio measured at a room temperature (23degrees centigrade). The closer the amplitude ratio difference is tozero, the more preferable the amplitude ratio difference is. It is mostpreferable that the amplitude ratio difference be substantially zero. InFIG. 26, a horizontal axis denotes the orthogonality [deg] whereas avertical axis denotes the amplitude ratio difference [%]. Note thatplots corresponding to the respective experimental examples 101A to101D, 102A, 102B, 103A to 103D, 104A, and 104B are denoted with theirrespective reference signs PL1A to PL1D, PL2A, PL2B, PL3A to PL3D, PL4A,and PL4B in FIG. 26. In FIG. 26, the experimental example 101A (FIG. 20)illustrates data corresponding to the sensor 133, the experimentalexample 101B (FIG. 21) illustrates data corresponding to the sensor 154,the experimental example 101C (FIG. 22) illustrates data correspondingto the sensor 135, the experimental example 101D (FIG. 23) illustratesdata corresponding to the sensor 158, the experimental example 102A(FIG. 24) illustrates data corresponding to the sensor 133, and theexperimental example 102B (FIG. 25) illustrates data corresponding tothe sensor 135. Further, in FIG. 26, the experimental example 103A (FIG.27) illustrates data corresponding to the sensor 1133, the experimentalexample 103B (FIG. 28) illustrates data corresponding to the sensor1154, the experimental example 103C (FIG. 29) illustrates datacorresponding to the sensor 1135, the experimental example 103D (FIG.30) illustrates data corresponding to the sensor 1158, the experimentalexample 104A (FIG. 31) illustrates data corresponding to the sensor1133, and the experimental example 104B (FIG. 32) illustrates datacorresponding to the sensor 1135.

As illustrated in FIG. 26, the experimental examples 101A to 101D, 102A,and 102B (the plots PL1A to PL1D, PL2A, and PL2B) according to theinvention showed improvement in the amplitude ratio as comparedrespectively with the experimental examples 103A to 103D, 104A, and 104B(the plots PL3A to PL3D, PL4A, and PL4B) according to the referenceexamples.

7. Other Modification Examples

Hereinbefore, although the invention has been described by referring tosome embodiments and some modification examples, the invention is notlimited to those embodiments, etc., and various modifications may bemade. For example, examples have been described in the foregoingembodiments, etc., in which three or four sensors are arranged in theX-axis direction or the Y-axis direction. The number of sensors,however, is not limited thereto in the invention. Any number isselectable for the sensors as long as the number is two or greater.Further, shapes and sizes of the respective sensors to be mounted to asingle sensor unit are not limited to a case where they are the same aseach other.

In addition, described in the foregoing embodiments, etc., is the sensorunit used as the angle detection sensor used for the detection of therotation angle of the rotating body. Use of the sensor unit according tothe invention, however, is not limited thereto. For example, the sensorunit according to the invention is also applicable to an electroniccompass that detects geomagnetism or other applications. Further, thesensor may include a detection device other than the magneto-resistiveeffect device, such as a Hall device.

It is to be noted that the invention is particularly useful for a casewhere a tunneling magneto-resistive device (TMR device) having the MTJfilm is employed as the magneto-resistive effect device, as comparedwith a case where a GMR device having the GMR film is employed. A reasonis that, in general, the TMR device is higher in sensitivity than theGMR device and is more susceptible to the stress applied to sensors(involves an increase in error more easily).

The present application is based on and claims priority from JapanesePatent Application No. 2016-140085 filed with the Japan Patent Office onJul. 15, 2016, Japanese Patent Application No. 2016-241461 filed withthe Japan Patent Office on Dec. 13, 2016, and Japanese PatentApplication No. 2016-000854 filed with the Japan Patent Office on Jan.6, 2017, the entire contents of which are hereby incorporated byreference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

The invention claimed is:
 1. A sensor unit comprising: a substratehaving a substantially-rectangular shape including a first side and asecond side that are substantially orthogonal to each other; a circuitchip stacked on the substrate; and a plurality of first sensors providedon a second surface of the circuit chip opposite to a first surface ofthe circuit chip, the first surface facing the substrate, and arrangedon a first axis, the first axis being substantially parallel to thefirst side and passing through a center position of the substrate or acenter position of the circuit chip, the plurality of first sensorshaving a plurality of sensor portions configured to output signals withdifferent phases in response to changes in an external magnetic field tobe detected.
 2. The sensor unit according to claim 1, furthercomprising: a plurality of leads each having one end provided on thesubstrate, and arranged along the first side or the second side, orarranged along both of the first side and the second side.
 3. The sensorunit according to claim 1, wherein one of the first sensors is a centerposition sensor provided at the center position of the substrate or thecenter position of the circuit chip, and the same number of theremaining first sensors, excluding the center position sensor, of thefirst sensors are provided on either side of the center position sensorto interpose the center position sensor.
 4. The sensor unit according toclaim 1, wherein the first sensors have respective rectangular shapesthat are substantially equal to each other, sizes, along the first side,of the respective first sensors are substantially same as each other,and sizes, along the second side, of the respective first sensors aresubstantially same as each other.
 5. The sensor unit according to claim1, further comprising: a plurality of second sensors provided on thesecond surface of the circuit chip and arranged on a second axis, thesecond axis being substantially parallel to the second side and passingthrough the center position of the substrate or the center position ofthe circuit chip.
 6. The sensor unit according to claim 5, wherein oneof the first sensors and one of the second sensors are each a centerposition sensor provided at the center position of the substrate or thecenter position of the circuit chip, the same number of the remainingfirst sensors, excluding the center position sensor, of the firstsensors are provided on either side of the center position sensor tointerpose the center position sensor, and the same number of theremaining second sensors, excluding the center position sensor, of thesecond sensors are provided on either side of the center position sensorto interpose the center position sensor.
 7. The sensor unit according toclaim 5, wherein the first sensors are disposed on the first axis with afirst distance provided therebetween that separates the first sensorsmutually, and the second sensors are disposed on the second axis with asecond distance provided therebetween that separates the second sensorsmutually.
 8. The sensor unit according to claim 7, wherein the firstdistance and the second distance are substantially equal to each other.9. The sensor unit according to claim 5, wherein the first sensors haverespective rectangular shapes that are substantially equal to eachother, sizes, along the first side, of the respective first sensors aresubstantially same as each other, sizes, along the second side, of therespective first sensors are substantially same as each other, thesecond sensors have respective rectangular shapes that are substantiallyequal to each other, sizes, along the first side, of the respectivesecond sensors are substantially same as each other, and sizes, alongthe second side, of the respective second sensors are substantially sameas each other.
 10. The sensor unit according to claim 9, wherein thesizes, along the first side, of the respective first sensors and thesizes, along the first side, of the respective second sensors aresubstantially same as each other, and the sizes, along the second side,of the respective first sensors and the sizes, along the second side, ofthe respective second sensors are substantially same as each other. 11.The sensor unit according to claim 5, wherein the first sensors and thesecond sensors each comprise a magneto-resistive effect device.
 12. Thesensor unit according to claim 1, wherein the center position of thesubstrate is coincident with the center position of the circuit chip.13. A sensor unit comprising: a substrate having a substantiallyrectangular shape including a first side and a second side that aresubstantially orthogonal to each other; a circuit chip stacked on thesubstrate; a sensor region in which a ratio of a second size in a seconddirection to a first size in a first direction is less than n where n isan integer equal to or greater than 2, the first direction beingsubstantially parallel to the first side, the second direction beingsubstantially parallel to the second side, the sensor region having asubstantially-rectangular shape and being provided on a second surfaceof the circuit chip opposite to a first surface of the circuit chip, thefirst surface facing the substrate; and n-number of sensors arrayed inthe sensor region in line in the second direction, and each having asubstantially-rectangular shape.
 14. The sensor unit according to claim13, wherein the ratio of the second size to the first size issubstantially one.
 15. The sensor unit according to claim 13, furthercomprising: a plurality of leads each having one end provided on thesubstrate, and arranged in the first direction or the second direction,or arranged in both of the first direction and the second direction. 16.The sensor unit according to claim 13, wherein the n-number of sensorseach have a first sensor size in the first direction and a second sensorsize in the second direction, and the first sensor size is larger thanthe second sensor size.
 17. The sensor unit according to claim 13,wherein all of the n-number of sensors have substantially the samerectangular shape as each other and have substantially the sameoccupancy area as each other.
 18. The sensor unit according to claim 13,wherein the substrate has a first substrate size in the first directionand a second substrate size in the second direction, the secondsubstrate size being substantially equal to the first substrate size.19. The sensor unit according to claim 13, wherein the n-number ofsensors having a plurality of sensor portions configured to outputsignals with different phases in response to changes in an externalmagnetic field to be detected.
 20. A sensor unit comprising: a substratehaving a substantially-rectangular shape including a first side and asecond side that are substantially orthogonal to each other; a circuitchip stacked on the substrate; a first sensor provided on a secondsurface of the circuit chip opposite to a first surface of the circuitchip, the first surface facing the substrate, and the first sensor beingprovided on a first axis, the first axis being substantially parallel tothe first side and passing through a center position of the substrate ora center position of the circuit chip, the first sensor having aplurality of sensor portions configured to output signals with differentphases in response to changes in an external magnetic field to bedetected; and a second sensor provided on the second surface of thecircuit chip and provided on a second axis, the second axis beingsubstantially parallel to the second side and passing through the centerposition of the substrate or the center position of the circuit chip.21. An electronic compass comprising: a substrate having asubstantially-rectangular shape including a first side and a second sidethat are substantially orthogonal to each other; a circuit chip stackedon the substrate; and a plurality of first sensors provided on a secondsurface of the circuit chip opposite to a first surface of the circuitchip, the first surface facing the substrate, and arranged on a firstaxis, the first axis being substantially parallel to the first side andpassing through a center position of the substrate or a center positionof the circuit chip, the plurality of first sensors having a pluralityof sensor portions configured to output signals with different phases inresponse to changes in an external magnetic field to be detected.
 22. Asensor unit comprising: a substrate having a substantially-rectangularshape including a first side and a second side that are substantiallyorthogonal to each other; and a plurality of first sensors provided inan area overlapping the substrate in a thickness direction, thethickness direction being orthogonal to a first direction along thefirst side and a second direction along a second side and arranged on afirst axis, the first axis being substantially parallel to the firstside and passing through a center position of the substrate, theplurality of first sensors having a plurality of sensor portionsconfigured to output signals with different phases in response tochanges in an external magnetic field to be detected.
 23. A sensor unitcomprising: a substrate; a sensor region in which a ratio of a secondsize in a second direction to a first size in a first direction is lessthan n where n is an integer equal to or greater than 2, the sensorregion having a substantially-rectangular shape and being provided in anarea overlapping the substrate in a thickness direction, the thicknessdirection being orthogonal to the first direction and the seconddirection; and n-number of sensors arrayed in the sensor region in linein the second direction, and each having a substantially-rectangularshape.